Flexible moulds

In the RI and RTMLight processes, the combined resin pressure and reinforcement resistance to compaction are sufficient to deform the top side mould. It is therefore important to be able to measure the mould deflections resulting in variation of the reinforcement properties [119]. 

Another specificity of flexible tooling is that the flow doesn t stop as the inlet is shut at the end of filling there is a pressure and thickness gradient remaining that needs to equilibrate to ensure a consistent and uniform quality to the finished part [76, 127, 128, 130-133], As the reinforcement compaction is provided by the pressure difference between the cavity and the environment, it is possible to have a limited control over the final part quality by controlling the vacuum pressure during post-filling [125, 134, 135], 

6 Comparison of the thickness and pressure traces during two iinear vacuum assisted resin transfer mouiding (VARTM) infusions (a) with iniet turned into a vent, and (b) with iniet ciamped at the end of fiiiing. 

As for rigid mould processes, one of the main goals of simulation is to minimise the trial and error development for manufacturing new parts. 

Hsiao et al. [143] looked at the optimisation of the flow distribution network for complex parts, to reduce the part defects and resin wastage. Lawrence et al. [144] evaluated the influence of embedded impermeable inserts on the resin flow during the RI process. However, both of those studies concentrated on the flow patterns, and did not take into account the dynamic changes in preform compaction and permeability. 

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Two-pack systems (sometimes known as RTV-2 rubbers). These are widely used for making flexible moulds, particularly for craft work. 

New copolymers with higher alpha olefins Expect superior ultimate properties Tough films, flexible moulding... 

Dabco NE1060 Newly developed non-fugitive gelling catalyst for flexible moulded applications. APCI... 

Machine runs for the MDI flexible moulded foam were conducted on a Krauss-Maffei, cylinder displacement series, high pressure machine. Fresh premixes, consisting of the appropriate polyols, water, crosslinker, surfactants and catalysts for each formulation were charged to the machine. Modified MDI was used throughout the entire study. All chemical temperatures were held at 25 °C 2 °C via the machine s internal temperature control units. Foam pours were made into an isothermally controlled heated aluminium mould maintained at 60 °C 2 °C. The mould was a typical physical property tool designed with... 

Flexible Moulded Foam Machine Physical Property Data... 

Dimensional Stabilising Additives for Flexible Polyurethane Foams 1.3.2.21 TDl Flexible Moulded Foam Review... 

Figure 1.41 shows a variety of flexible moulded Dabco surfactants which can be utilised in TDI and/or MDI formulations. Using Figure 1.41, proper selection of the surfactant can be made, enabling polyurethane formulators to expand their processing latitude, cell openness, and bulk stability of the foam article in their critical formulations. 

Figure 1.41 Flexible Moulded Surfactant/Property Relationships...

Tables 1.38 and 1.39 provide the physical property comparison for the 55 kg/m MDI flexible moulded formulations XXV-XXXIV. The data clearly demonstrates that physical properties are maintained, and in several cases improved, compared to the control formulations, depending on the formulation. For example, the data in Table 1.38 illustrates that all physical properties are matched to the control formulation (XXV) at an index of 105 with the exception of a slightly lower ball rebound for the full non-fugitive catalyst package. At an index of 105, all physical properties for the experimental non-fugitive catalysts formulations were determined to be similar to the control (XXX). When Dabco NE1060/BL-11 is used as a low emission catalyst package (XXXHI), all physical properties at the index of 105 are comparable to the control foam. At an index of 105 (XXXHI), airflow, elongation and Japanese wet sets and HACS are improved over the control (XXX) and 50% dry compression sets are slightly elevated.

The information below highlights the features characteristic of the TDI and the MDI flexible moulded models. Table 1.45 illustrates the conversion of the formulations from Tables 1.12-1.15 into a TDI model system. Table 1.46 illustrates the conversion of the formulations from Table 1.35 into an MDI model system. 

Table 1.45 TDI flexible moulded foam model system...

Details on the development and use of foam model systems for flexible moulded foam have been published [14]. In this section the features characteristic of slabstock foams will be highlighted. Table 1.47 illustrates the conversion of the formulations from Table 1.42 into a model system. 

Flexible moulded polyether foam is widely used in the transport, furniture and packaging sectors. In many cases flammability is of great importance and so the effects of suitable flame-retardant agents on such foams has been widely studied. One piece of work by Chestnut Ridge Foam in Pennsylvania, using Cone Calorimetry, studied the heat release characteristics of various combinations of commercially available additives, plus the CO emission and time to ignition. 

Hydraulic seals C lular products Flexible moulds Sprayed products Encapsulation Pneumatic drill handles... 

Journal papers focused on flexible mould processes... 

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